One of my favorite apps is Adobe Kuler. It makes you look at the world, and your photographs, differently. You can see below, this is the iphone app opening screen, which uses your camera. Immediately it starts identifying the main colors in your image/camera viewfinder. Here is my pencil cup, and you can see the main colors immediately becoming a color palette for me. I can then save it to my kuler account.
My other options include switching to photo view mode, and creating a color palette from a photo you've already taken. Once I've saved the palette, below, I can go into it and alter the colors completely or just tweak them. Then I can share on facebook, twitter or email etc. The HEX and RGB codes are a bonus, cause then I can match colors in paintings or photoshop.
You can see the link in the Kuler website here.
On the website you can also alter the colors, share the color scheme with other kuler users, etc. This is a great app!! Get addicted to color!